package ch.dola.minecraft.lastlogin;

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintStream;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

public class Main {

	/**
	 * Decrypts the username and password from the minecraft lastlogin file, which contains the last saved login informations.
	 *
	 * @param args[0] The path to the lastlogin file in the minecraft directory
	 */
	public static void main(String[] args) {

		PrintStream out = System.out;
		PrintStream error = System.err;

		out.println("Starting Minecraft lastlogin decryptor");
		out.println("--------------------------------------");
		out.println();
		if(args.length >= 1){
			out.println("Inspecting file at " + args[0]);
			LastLoginDecryptor lld;
			try {
				lld = new LastLoginDecryptor(args[0]);
				out.println("Trying to decrypt data...");
				out.println();
				out.println("Username extraced: " + lld.getUsername());
				out.println("Password extraced: " + lld.getPassword());
			} catch (FileNotFoundException e) {
				error.println("Error: Specified File was not found.");
			} catch (IOException e) {
				error.println("Error: Could not read from specified file. Maybe permission is missing.");
			} catch (Exception e) {
				error.println("Error: An unknown error occured: ");
				e.printStackTrace();
			}

		} else{
			out.println("Usage:");
			out.println("java -jar lastlogindecryptor.jar FILENAME");
			out.println("or make your own executable .sh file including the following line:");
			out.println("java -jar lastlogindecryptor.jar $1");
		}
	}

	static class LastLoginDecryptor {

		String password = null;
		String username = null;

		boolean decrypted = false;

		DataInputStream in;

		public LastLoginDecryptor(String filePath) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException, InvalidKeyException, InvalidAlgorithmParameterException, FileNotFoundException{
			Random random = new Random(43287234L);
			byte[] salt = new byte[8];
			random.nextBytes(salt);
			PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 5);
			SecretKey pbeKey = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(new PBEKeySpec("passwordfile".toCharArray()));
			Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
			cipher.init(2, pbeKey, pbeParamSpec);

			in = new DataInputStream(new CipherInputStream(new FileInputStream(filePath), cipher));
		}

		private void decrypt() throws IOException{
			username = in.readUTF();
			password = in.readUTF();
			in.close();

			decrypted = true;
		}

		public String getPassword() throws IOException{
			if (!decrypted){
				decrypt();
			}
			return password;
		}

		public String getUsername() throws IOException{
			if (!decrypted){
				decrypt();
			}
			return username;
		}
	}
}